(1) Field of the Invention
This invention relates to the preparation of silane, SiH.sub.4. This gas is a useful chemical intermediate. It has important and growing usage in the production of electronic equipment and devices. The invention also pertains to the formation of amine alanes, AlH.sub.3.NR.sub.3. These materials, which are stabilized forms of AlH.sub.3, are also useful as chemical intermediates. For example, they can be reacted with a silicon halide such as SiCl.sub.4 or SiF.sub.4 to produce additional silane.
(2) Related Art
Reference is made to U.S. Pat. No. 4,474,743. It pertains to production of silane and aluminum fluoride from silicon tetrafluoride and amine alanes. Reference is also made to U.S. Pat. No. 4,006,095. It teaches, inter alia, that SiCl.sub.4 reacts with an amine solution of AlH.sub.3.
U.S. Pat. No. 4,474,743, cited above, contains a citation to U.S. Pat. No. 4,006,905. It also sets forth other prior art relating to amine alane production. For example, it sets forth the following general methods for preparing amine alanes: ##STR1##
U.S. Pat. No. 4,474,743 also states that:
"Alane, that is aluminum trihydride or AlH.sub.3, has in the past been produced from the reaction of LiAlH.sub.4 and AlCl.sub.3 in ethers. Also known is the production of an alane dimethyl ether solution from the reaction of LiH and AlCl.sub.3 in dimethyl ether, catalyzed by NaAlH.sub.4.
Amines are used to produce amine alanes for subsequent syntheses. For example, LiAlH.sub.4 can be reacted with a trialkyl amine.HCl complex to precipitate LiCl and form AlH.sub.3.NR.sub.3 where R is alkyl."
It is known in the art that lithium aluminum hydride reacts with silicon tetrachloride. This process is set forth in Kelly, British Pat. No. 823,496. In that reference the reaction is depicted by the following equation: EQU SiCl.sub.4 +LiAlH.sub.4 .fwdarw.SiH.sub.4 +LiCl+AlCl.sub.3 (5)
Allied, British 851,962 sets forth the analogous equation: EQU SiCl.sub.4 +NaAlH.sub.4 .fwdarw.SiH.sub.4 +NaCl+AlCl.sub.3 (6)
Padma, D.K. et al., Journal of Fluorine Chemistrv, 1979, Volume 14, pages 327-329, teaches that SiF.sub.4 reacts with LiAlH.sub.4 to form silane. The by-product(s) of the reaction were not described in the reference.